This invention relates to polymer compositions containing hydrogenated block copolymers of vinyl aromatic hydrocarbons and conjugated dienes, processing oils and polyolefins. More particularly, the present invention relates to such polymers which are made both soft and paintable.
Polymer compositions containing the above block copolymers, processing oils and polyolefins are well known. They usually additionally comprise a filler compound. Such compositions have been used in the automotive industry for molded parts such as grommets, sound barriers and air ducts. However, these compositions are relatively hard and are not easy to paint with polyurethane-based paints. Since these compositions do have other advantages, such as very good low temperature brittleness, which make them quite useful in many applications, including automotive applications, it would be a distinct advantage if a way could be found to make such compositions paintable and soft so that they could be used in the manufacture of padded car door parts, arm rests and other materials which require the combined characteristics of such polymers including flexibility, excellent resistance to ozone, UV radiation and weather, good heat and chemical resistance and are easily processable. The advantages of such compositions are described in "Automotive Applications of Styrenic Thermoplastic Elastomers" by Geoffrey Holden and Kyle H. Speer, Automotive Polymers and Design, 58, No. 3, February 1989.
In many automotive interior applications, there is a need for parts with a rigid substructure and a soft surface. Some examples are steering wheels, instrument panels, air bag doors and consoles. Such parts can be both functionally and aesthetically effective. Functionally, they can serve to reduce injuries caused by collisions. Aesthetically, they give a more attractive appearance and luxurious feel to the interior, which many buyers prefer to the current systems. For both these reasons, the use of soft surfaces molded over a rigid substructure is growing.